An exterior mirror assembly for automobiles typically includes a mirror sub-assembly with a carrier plate that holds an exterior mirror and also movably connects the mirror subassembly to other parts of the exterior mirror assembly such as an exterior mirror housing and a motor pack. Historically, exterior mirror structures usually did not include any electronic circuitry or other added features that enhance the functions of the mirror or the automobile. Such enhanced features as there were, often were driven remotely by electronic circuitry in the body of the vehicle. Recently, however, it is common to add electronic circuitry to the exterior mirror assembly to provide enhanced features, such as antennas, security lights, signal modules, heaters, electrochromic mirror elements, light sensors, and the like. For some of these enhanced features on exterior mirrors, the carrier plate provides a convenient structural support for the electronic components as well as the mirror itself in the mirror sub-assembly. Heretofore, such electronic components have been mounted on a discrete circuit board on the carrier plate and covered for protection against environmental contamination.
One problem with such mountings is that sufficient volume must be maintained in the mounting to dissipate heat generated by the circuitry. The corresponding volume consumes excessive space within the mirror housing and creates a protrusion from the rear of the carrier plate with a resultant uneven profile extending rearwardly of the carrier plate. For example, in a mirror assembly having a heater to remove ice or mist from the mirror glass, the heater is attached to a front side of the carrier plate on its own heater substrate, adjacent to the mirror glass. The motor pack, an electronic circuit board, and assorted electrical connectors between the circuit board and the heater and motor pack are mounted to the rear of the carrier plate. With this arrangement, the sub-assembly has a relatively high, uneven profile, requiring additional space in the housing to accommodate the motor pack and the limits of motion of the mirror subassembly. This profile will also interfere or displace other electronic components in the mirror housing.
Additionally, because exterior mirrors come in a wide variety of shapes, dimensions, and radii of curvature, the uneven profile caused by the differing electronic circuitry necessitates a custom-designed carrier plate for different vehicles.